Protocol Independent Management (PIM) is a routing scheme using existing unicast routing protocols, e.g., RIP, OSPF, BGP etc., that provides a mechanism to send IP data packets to a set of receivers, while reducing as much as possible the number of replicated data packets. Multicast protocols enable the delivery of information from a sender to a set of receivers. It is a generalization of the concept of unicast transmission, where the information is transmitted from a sender to a single receiving network. It is also a generalization of a broadcast, where the information is transmitted from a sender to all possible destinations.
FIG. 1 illustrates an exemplary unicast protocol delivery system 100 wherein source node 110 provides information to each of the receiving networks 140.1, 140.2, 140.3 through network 115. In this illustrative example, source node 110 is required to know in advance the associated receiver addresses and each data packet is replicated at the source to provide one copy for each receiver.
FIG. 2 illustrates an exemplary IP Multicast protocol system that improves upon the simple unicast transmission shown in FIG. 1, wherein IP packets are sent to every interface, of a router i.e., node 1301, in the broadcast domain. In the illustrated case, source 110 needs only to know a multicast group address. A multicast group represents a group of receivers, illustrated as receiving networks 140.1, 140.2, 140.3, that participate in the multicast communication. In this case, the IP packets are replicated as close to the receiver as possible. For example, the replication of packets destined to the receiving networks in Group ABC is performed at the node 130.1 attached of the receivers in Group ABC.
The Protocol Independent Multicast (PIM) standard, together with Internet Group Management Protocol (IGMP) define the logical protocol entities that implement multicasting. These well-known protocols define a Multicast group, which represents a group of users that subscribe to the same information stream. Further defined are entities such as a Rendezvous Point (RP) that represents the root of a multicast tree connecting a sender (transmitting node) to the receivers (receiving nodes or networks) and to which all Multicast users subscribe in order to send and receive the multicast stream. A Sender represents a device that sends information to a multicast group and a Receiver represents a device that receives information destined for a multicast group. Further defined is a Designated Router (DR), which represents a local router within a subnet that sends registration packets to the RP on behalf of the senders or receivers and a Bootstrap Router (BSR) which represents a device containing a list of multicast candidate RPs within a PIM domain.
FIG. 3A illustrates an exemplary multicast network wherein IP packets from source 110.1 are transmitted though node 120.1, node 125.1, which is referred to as an RP, and node 130.1, which is referred to as a DR, to networks 140.1-140.3 in Group ABC. Also illustrated is the transmission from source 110.1, through nodes 120.2, 125.2, to RP node 125.1 and DR node 103.1 for subsequent transmission to networks 140.1-140.3 in Group ABC. In each of these cases, the multicast IP packets are processed through RP 125.1.
FIG. 3B illustrates the operation of transmission between autonomous systems (AS) 310, 320 using a MSDP protocol between RP 125.1 in AS 310 and RP 125.3 in AS 320. MSDP protocol is well-known to allow transmission of multicast packets between autonomous systems and need not be discussed in detail herein.
With the complexity of the multicast network configuration and the ability to add or remove nodes and networks from the multicast network, the identification and management of Multicast networks presents a burden on system administers as failures in configuration setup or physical node failures may be detrimental to only some aspects of the network operation and not others. For example, a failure in configuration setup, which is typically performed manually or, in cases, automatically, may cause nodes to be not responsive to data traffic flow or commands while a physical failure in a node may cause a complete or partial network failure operation. With reference to FIG. 3A, a failure occurring at node 125.1 will prevent networks 140.1-140.3 from receiving any data, whereas a failure occurring at node 125.2 will enable networks 140.1-140.3 to receive data from source 110.1 only.
Hence, there is a need in the industry for a method and system that can automate the management of the discovery of the configuration and operation of the multicast network layers and further determine and analyze the source of alarms generated at different levels of the network.